The term "sea water" as used herein is intended to refer to ocean water, and the like, having a sufficiently high total dissolved solid content so that the water is unusable for agricultural purposes. The term "desalinated water" used herein is intended to refer to water in which the total dissolved solids are reduced to a level sufficient to render the water at least suitable for irrigation purposes.
The system of the present invention has general utility in that it enables desalinated water to be produced in any desired quantity at negligible cost. The system is advantageous in that apart from pumps, it does not entail any moving parts; nor does it require the introduction of heat, pressure or electricity from external power sources. In addition, the system of the invention has the capability of operating over prolonged periods of time without any noticeable deterioration of its components, and without the need for any substantial maintenance or servicing operations. In addition, the system of the invention has an advantage in that it utilizes relatively inexpensive and readily available materials in accomplishing its desired results.
Although the theoretical principles upon which the operation of the system of the invention is predicated are not completely understood, it is believed that the filter materials contained in the barrier which, in accordance with the concepts of the invention, are imbedded in the sand of a beach, set up an ion-exchange reaction in the saline or brackish solution passing through the barrier, and this ion-exchange reaction causes a desalinated water separation, with the lighter desalinated water flowing above the heavier brine or brackish solution through the sand and into the opening in the vault, which is also imbedded in the sand. The desalinated water passes through the opening in the side of the vault and into its interior, whereas the heavier brine solution is dispersed in the sand under the barrier and the vault; or may be pumped to waste through an appropriate drainage system installed below the level of the barrier and the vault opening.
Also, the sap of the guayule plant, family asteraceae, genus parthenium argentatum, is placed in the sand between the barrier and the vault, and this sap reacts with residual compounds in the sea or brackish water after passing through the barrier to cause such heavier materials to gravitate down into the brine solution underlying the upper layer of desalinated water. The only maintenance required in the system is to add additional sap to the area after several months of operation. The quantity of sap to be used, and the quantities of the materials in the barrier are not critical. The addition of the guayule sap to the area between the barrier and the vault opening also serves as an organic wetting agent and increases the water velocity through the intervening sand. Should these sands be very small and dense, thereby greatly retarding water flow, replacement with small size gravel is desirable to increase the water velocity. Guayule sap at the rate of 100 liters per cubic meter of the sand between the barrier and vault opening has proven very effective in producing desalinated water of a potable quality as low as 55 parts per million. In the event water quality should decrease, the addition of guayule sap to the filter materials in the barrier may be effected to re-enforce the desalinating performance of the system.